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Squalicorax
Squalicorax, also known as the crow shark or raven shark, is a species of extinct lamniform shark in the family Anacoracidae. Hailing from the Cretaceous period (and seemingly into the Cenozoic), Squalicorax was one of the most widespread sharks of its time. Etymology As its common name and scientific name suggests, Squalicorax's name comes from the Greek words for shark (squalus) and raven (corax). Description Squalicorax was of medium size, up to 5 m (16 ft) maximum (usually around 2 m (6 ft)) in length. Their bodies were similar to the modern gray reef sharks in shape, but the shape of their teeth is strikingly similar to those of the tiger shark. The teeth are numerous, relatively small, with a curved crown and serrated, up to 2.5 – 3 cm in height ( Squalicorax was the only representative of the Mesozoic Lamniformes with serrated teeth). Large numbers of fossil teeth have been found in Europe, North Africa, and North America. Squalicorax was a coastal predator, but also scavenged as evidenced by a Squalicorax tooth found embedded in the metatarsal (foot) bone of a hadrosaurid (duckbill) dinosaur that most likely died on land and ended up washing into the water. Other food sources for Squalicorax likely included turtles, mosasaurs, ichthyodectes, and other bony fishes and sea creatures. Fossil evidence also indicates they may have hunted the pterosaur Pteranodon, but whether these sharks were agile enough to snatch these giant flying reptiles out of the air is not known. Additionally, Squalicorax shared its environment with the distantly related ''Cretoxyrhina'', another lamniform, with which it may have scavenged the kills of or competed with for food. Notable Species * Squalicorax falcatus (Agassiz, 1843) – is a medium-sized shark with a broad snout and relatively small teeth. Its length reached almost 3 m (10 ft). It lived during the Cenomanian to early Santonian (Campanian). Complete skeletons are known from sediments of the Western Inland Sea of the Cretaceous in Kansas, South Dakota, and Wyoming, all in the USA. The teeth are also found in France, the Czech Republic, Canada, and Morocco. Given the small teeth, this species is considered a hunter of small prey. However, teeth marks on the bones of marine reptiles are evidence that these shark also fed on carrion. The body shape and structure of the trunk placoid scales indicate the ability to swim quickly. A fully articulated 1.9-m long fossil skeleton of Squalicorax falcatus has been found in Kansas, evidence of its presence in the Western Interior Seaway. * Squalicorax kaupi (Agassiz, 1843) is from the late Santonian to the late Maastrichtian of North America, New Zealand, Japan, Africa, Europe, Kazakhstan, Jordan. and other places. It was slightly larger than the preceding species, of which it was probably an ancestor. * Squalicorax pristodontus (Agassiz, 1843) is the largest species, more than 5 m long. From the size of its largest known teeth, it can be estimated that S. pristodontus ''grew to 5 m (16.5 ft) in length. It lived during the late Campanian to early Maastrichtian of North America, France, the Netherlands, Egypt, Morocco, and Madagascar. The relatively complete remains (vertebrae and fragments of jaws) have been found in marine sediments in North America. It is the species with the largest teeth, these teeth being loosely spaced and relatively very large in comparison with other species. In this genus of sharks studies have shown no precise correlation between the size of the teeth and the length of the body. They could eat relatively large prey and carrion. * ''Squalicorax volgensis - the oldest species of the genus, from the Early Cretaceous of the Volga – has been described by L. Glickman et al. in 1971. The teeth of this species had virtually no serrations. They are known from the Albian to the Turonian Age in Eastern and Western Europe, as well as Texas. Teeth have also been found from the Albian in Angola and Australia, as well as the Cenomanian and Santonian Ages in Egypt, Kazakhstan, and Russia. Finding the teeth of these sharks in the Cenozoic sediments shows that this genus probably did survive the Cretaceous-Paleogene crisis. The world's largest and most complete semiarticulated fossil of Squalicorax was found in 2014 in stores of the Canadian Fossil Discovery Centre in Morden, Manitoba, in Canada, where it is now displayed. It measures more than 3 m (10 ft) in length. Extinction Squalicorax is believed to have gone extinct as a result of the K-Pg event wiping out the large marine reptiles it fed upon. Without such prey as mosasaurs, giant turtles, and plesiosaurs to scavenge or hunt, the shark was doomed to fade into extinction. Squalicorax's extinction in turn opened up niches for the rise of large requiem sharks that were quick to fill the empty niche. List of Species There are close to 18 different species of Squalicorax known to science. * S. africanus * S. appendiculatus * S. baharijensis * S. bassanii * S. bernardezi * S. coquandi * S. curvatus * S. falcatus * S. heterodon * S. kaupi * S. kugleri * S. lindstromi * S. primigenius * S. priscoserratus * S. pristodontus * S. sagisicus * S. volgensis * S. yangaensis Category:Chondrichthyes Category:Elasmobranchs Category:Sharks Category:Lamniformes Category:Anacoracidae Category:Squalicorax Category:Prehistoric Sharks